1. Field of the Invention
The present invention relates generally to the excavation of cylindrical holes for pilings and other vertical supports and has particular reference to an improved cable supported blade and casing arrangement adapted to excavating a cylindrical hole without the use of cumbersome drilling elements.
2. Background of the Invention
To adequately support a heavy structure on unstable ground, it is frequently necessary to provide piles or other supports between the base of the structure and a more stable stratum well below the base. These supports may consist of steel or timber driven into the ground. Often, however, they consist of reinforced concrete formed in place in a hole that has been excavated to the desired depth.
Typically, the hole is bored into the ground by a large auger, known as a Kelly bar, which must be supported and maneuvered by a machine able to both rotate the Kelly bar about its longitudinal axis and lift the Kelly bar from the hole to clear dirt and other debris. Since a Kelly bar may be fifty feet long, it is usually hung from a crane and fitted to a rotational drive mechanism mounted to the derrick of the crane.
The depth to which a hole may be bored by this method is limited to the length of the Kelly bar used. Should it be necessary to bore a deeper hole than initially anticipated this may require the use of a second, longer Kelly bar.
It is therefore an object of this invention to provide an improved excavation means to overcome or substantially reduce the aforementioned problems associated with auger conveyor excavation.
More specifically it is an object of this invention to provide a bucket-type excavation device which does not require rotational drive means.
A further specific object of this invention is to provide an easily operable excavating device whose digging blades also serve as the bottom to the bucket-like device.
Other and further objects of this invention will become apparent to those skilled in this art from the detailed description of a preferred embodiment of the apparatus for use in accordance with the present invention.